1. Cancer Prevention Studies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD
2. Cancer Institute, Chinese Academy of Medical Sciences, Beijing, People's Republic of China
3. Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, MD
4. Department of Biochemistry, Rollins Research Center, Emory University, Atlanta, GA
5. Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD